Direct Drive Banki Hydro

Pictured above is our neighbor Scott's Dam. He's got a 4" diameter PVC pipe out of it, running down the creek about 15'. The total head here is about 3'. Our goal is to build a small hydro electric plant. In the past he had a machine he'd built from a squirrel cage blower, with a belt, to a PM DC motor. It produced about 1 amp, give or take a bit and he ran it year round for 2 years. It provided most of his power during that time, more than enough for a couple lights and a radio. Scott came up this spring and helped build a wind turbine for his place. We figured, if we built a similar alternator for the hydro plant, that we did for his wind turbine, and perhaps improved the wheel a bit, we could capture a bit more power from this dam!

We started with scraps of sheet metal and angle iron. The disks for the runner were made from the base of a dead Onan Generator. The alternator was built from two 11" diameter brake rotors (we think they are off a Dodge but not sure), and the spindle/wheel hub also... probably from a Dodge, but were not sure because it was salvaged off other homemade equipment.

The Vanes in the runner are made from quartered 4" diameter steel conduit.

The sides of the runner are 12" diameter. We made a template which helped lay out the holes to fit the runner to the wheel hub (5 lugs) and layout the exact position, and angle of the vanes. The idea behind this was to make something along the lines of a "Banki" turbine, which looks a lot like a squirrel cage blower. In the Banki turbine, if one was looking at the side, the water should enter below the top (perhaps around 10 O'clock), pass through the middle of the wheel, and exit near the bottom (around 5 O'clock), so the water actually hits the vanes twice. We looked at lots of pictures and took our best guess regarding the width, and angle of the vanes. Pictured above were punching all the locations for the edges of the vanes, and the holes which will mount the runner to the alternator. The runner has 16 vanes.

The template is glued to one of the disks which make up the sides of the runner, and we have both disks clamped together. Pictured above we're drilling small holes which will help us know exactly where to postion the vanes.

We put 10" between the two sides of the runner using allthread, and squared it up as best we could before installing the vanes. You can see some of the holes we drilled to help with postioning the vanes.

Here the runner is getting welded up. It's important to note... the vanes are made of galvanized steel conduit. We had to grind all the galvanization (Zinc) off the edges before welding this... welding galvanized metal produces toxic gas, so we try to be careful about this.

Pictured above the runner is pretty well tacked together. We'll add a bit more welding later. It's not been shown yet (but later will be), one side of the runner (the side opposite the alternator) has a 4" diameter hole in in the middle, so that we could more easily bolt it to the alternator, and get our hands in there to remove sticks and such that might get stuck in it.

The nozzel will be the same width (10") as the runner, and it's about 1" wide where the water exits. This gives about the same area at the end of the nozzel as the 4" pipe that feeds it... slightly less. Pictured above we're bending the sheet metal which makes it up.

Pictured above it's starting to take shape. We've mounted the runner to the hub, and basicly assembled everyting except for the alternator. Everything on this is adjustable. We can move the nozzel forward, back, up, and down. The runner (and the alternator) can be moved back, and fourth.